An ignition system of this general type is already known from U.S. Pat. No. 4,204,508, which corresponds to German Patent Disclosure Document DE-OS No. 2 701 967. In that prior system, however, the limitation of the current flowing through the primary winding of the ignition coil and the furnishing of control current to the base of the output switching transistor are both associated with a relatively high power loss. This is because the output transistor is driven in the active domain while limiting the current through the primary winding, and during the furnishing of the control current to the base of the output transistor, a substantial amount of power is converted into heat by resistors through which this control current flows.